Sin400°=

1. sin40°

2. - sin40°

3. sin (-40) °

sin (40°)

Step-by-step explanation:

Trigonometric functions such as sine, cosine, tangent whose short forms are sin, cos, tan respectively are repetitive functions which repeat itself after every integral multiple of 2π radian or 360°. It means if you add or subtract 360° from any input of trigonometric function the output of the function won't change.

It means sin (θ) = sin (θ - n*360°) = sin (θ + n*360°)

similarly cos (θ) = cos (θ - n*360°) = cos (θ + n*360°)

and tan (θ) = tan (θ - n*360°) = tan (θ + n*360°)

where n is an integer.

So, by this sin (400°) = sin (400° - 360°) = sin (40°)